China has long had a large population. In 1897 the country contained 363 million people — still 45 million more than the current population of the US.

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It wasn't until a century later, however, that the rural Pearl River Delta began to take shape as an urban hub during the tech and manufacturing booms of the 1990s.

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By the early 2000s, the changes were plainly visible. Take the NASA satellite photography over a period of 30 years. Here's 1973. The wispy gray regions are the infrastructure projects quickly popping up around the region.

Over the next several years, populations truly began to explode. The nine cities' populations each eclipsed the 1-million mark.

Finally, in 2008, the Chinese government announced its official plans to merge the nine cities into one gigantic "megacity."

To make the Pearl River Delta megacity a reality, China has been rapidly scaling up its construction of bridges, highways, railways, hospitals, and factories.

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With a finite amount of land, that has meant demolishing existing structures that are either old or in disrepair. Here, a residential high rise is razed to make room for a traffic hub.

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In certain cases, individual homes get caught in the crossfire. For instance, the government in Guangzhou accidentally demolished one woman's home during a routine project.

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Overwhelmed with the sense of loss, the woman, Huang Sufang, later leapt from a building to her death. Though a rare case, her suicide highlighted how profoundly the plan can affect China's residents.

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On top of that, the construction process hasn't been uniform. Soaring factories rise before existing shanties are torn down, leading to jarring cityscapes, like this one in Guangdong province.

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And of course, China faces the ongoing problem of pollution. Its air is some of the dirtiest in the world, and its rivers are frequently overrun with garbage — both high hurdles if the country wants to scale up manufacturing even more.

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If the country hopes to achieve its goal of moving 80 million people inside the Pearl River Delta's border by 2030, it will need to convince the majority of people to relocate.

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According to a recent World Bank report, some 64% of people still live in non-urban areas in the Pearl River Delta.

That has left many apartment buildings fully constructed, but totally vacant.

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This will be the challenge for the Pearl River Delta moving forward. By 2030, China plans to spend $322 billion in the hopes of drawing more people into urban areas from the outskirts of the megalopolis.

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If all goes to plan, the region will be so well-connected that people can travel between any two points in under an hour. The 100-mile-long Express Rail Link, for instance, will cut times between Hong Kong and Guangzhou from two hours to 48 minutes.

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"Within a few decades, this window of opportunity will close," the World Bank report states, "and future generations will be left to deal with the consequences of how we urbanize today."